1. Field of the Invention
The present invention relates to a wireless device provided with an antenna, more particularly relates to a wireless device as a mobile wireless device where the orientation of the antenna is not fixed.
2. Description of the Related Art
As typical examples of mobile wireless devices where the orientation of the antenna is not fixed, there are mobile phones, notebook PCs, etc. In wireless devices such as these mobile phones and notebook PCs, in recent years, wireless devices have appeared which have to be able to send and receives signals carried on a plurality of polarized waves.
As examples, there are mobile phones provided with antennas for GPS and other wireless communications and notebook PCs able to connect to wireless local area networks (LAN). These mobile phones and notebook PCs have to mount circular polarized wave patch antennas and have to be able to send and receive two types of polarized waves, that is, a right hand circular polarized (RHCP) wave (first polarized wave) and a left hand circular polarized (LHCP) wave (second polarized wave). Note that, as relationships between the “first polarized wave” and the “second polarized wave” referred to here, other than that described above, there are a “linear polarized wave” and a “circular polarized wave”. The following explanation will be given by taking as an example the circular polarized waves including the “right hand circular polarized wave” and the “left hand circular polarized wave”. As the mobile wireless devices described above, an explanation will be given by taking as an example a mobile phone, particularly a GPS-capable mobile phone mounting a circular polarized wave patch antenna.
As the known art related to the present invention, there are Japanese Patent Publication (A) No. 2005-286854, Japanese Patent Publication (A) No. 1999-186947, and Japanese Patent Publication (A) No. 2000-243926. Japanese Patent Publication (A) No. 2005-286854 describes an antenna having a polarized wave switching function, Japanese Patent Publication (A) No. 1999-186947 describes a mobile communication terminal able to secure a transmission/reception sensitivity regardless of an opened/closed state of a cover including the antenna, and Japanese Patent Publication (A) No. 2000-243926 describes a patch antenna having one of a patch electrode or a ground plane emit a right hand circular polarized wave to the front and having the other emit a left hand circular polarized wave to the front.
Summarizing the problem to be solved by the invention, a GPS-capable mobile phone receiving a right hand circular polarized (RHCP) wave and a left hand circular polarized (LHCP) wave conventionally mounted a patch antenna optimizing the reception sensitivity for just one of these, for example, RHCP.
However, in recent years, so-called flip-open type mobile phones configured by a fixed part and a movable part which can be opened/closed with respect to this fixed part have begun to be widely used. The circular polarized wave patch antenna is mounted on the movable part side (the side having an LCD display surface). There is therefore the problem that when designed so as to optimize the reception sensitivity in the open state, the reception sensitivity deteriorated in the closed state (or vice versa). Particularly, in GPS-capable mobile phones, it is important to enable the reception of GPS signals and enable constant transmission of current location information not only at the time of usual use (above open state), but also at the time of nonuse (closed state described above).